Rotors of screw compressors are already known from JP 2004324468 and JP 1237388, whereby these rotors are provided with a shaft in which is provided an inner, central and axially directed cooling channel where cooling oil is sent through so as to improve the efficiency of the compressor.
Such known rotors do no allow for a proper, efficient conditioning of the rotor geometry over a wide operational range, however.
From SE 517.211 is already known a rotor in which is provided a cooling channel with a turbulence amplifying element in it, made of polymer in the shape of a spiral element.
In practice, it turns out that such a turbulence amplifying element does not provide the hoped-for result either of a proper, efficient conditioning as far as heat transfer is concerned; moreover, especially with liquids, there will be additional pressure drops.